Timing at full advance?

[troutmalt]

1968 302V8. Finally I got the numbered timing mark tape indexed onto the harmonic balancer. I have set my static timing at @ 10 degrees BTDC.

Problem is full advance should be @ 36 degrees and I show 24 degrees at high RPM.

No vacuum pot - Pertronics electronic module in distributor which is a trigger only - no advance.

Only place I can think to go is a sticky centrifical advance mechanism?
Any other thoughts?.

[KULTULZ]

Originally Posted by troutmalt

1968 302V8.

Finally I got the numbered timing mark tape indexed onto the harmonic balancer. I have set my static timing at @ 10 degrees BTDC.

Problem is full advance should be @ 36 degrees and I show 24 degrees at high RPM.

No vacuum pot - Pertronics electronic module in distributor which is a trigger only - no advance.

Only place I can think to go is a sticky centrifical advance mechanism?

Any other thoughts?.

Just one -

- POSTED 11-13-2022 - 08:55 P.M. -

Originally Posted by KULTULZ

To help you, we have to know what DIST it has, plain as that.

[cadillac512]

As Kultulz says, best is the dist number from the side of the housing. BUT, a couple general things to consider:


Are you setting initial timing at an rpm that you are sure no centrifugal advance is occurring?


When twisting the rotor does it move freely and snap back as it should?


When you check advance are the results repeatable?

[miker98038]

I really don’t know anything about those Mustangs, except for briefly owning a 67 390, which was a regular little rocket ship. But from what I can find, and how I understand it, the only 302 in 1968 was the 230 hp with 10.0 static compression ratio. Can’t see if it was a centrifugal only distributor, or had a vacuum advance also. Irregardless., in those years and after, premium fuel was sometimes difficult to find and expensive. I suspect someone modified that distributor to slow down and/or limit the total advance. Typically kits are available in the aftermarket to do that. Some combination of weights, springs, sometimes bushing, depends on the distributor involved.

Without the number, K isn’t going to be able to find an oem spec. If you’ve got enough experience or information, you might be able to change that in the car, or recognize what’s been done. If not, it’s going to have to come out and at that point you find a speed shop with a distributor machine and all the specs available. None of this was rocket science back in the day, but even a 3 bay gas station would possibly have a distributor machine and a guy who knew how to use it. Now days, not so much is available, hence a speed shop.

Cadillac beat me to some of that, ands makes some other good points (pardon the pun).

[troutmalt]

Thanks all for the great support. The distributor is stock Ford but the vacuum pot has been removed and sealed. It is 1968 Mustang 302 V8.
the Pertronics trigger module has no effect on ignition timing.

Static timing is @ 10 degrees BTDC at 800 RPM. Best advance I can get is 24 degrees BTDC. Results are repeating exactly.

The comment about twisting the rotor is excellent idea before I have to remove the points plate to expose the centrifical mechanism. Thanks for that.

Unfortunately, it will be hard to tell if I am getting full movement on the weights until I take it apart. Maybe it will appear a bit sticky indicating a problem.

ps – Teach me - what difference does it make what the number is on the distributer?
Don’t most all cars of this era run @ 36 degrees of full advance at about 3.000 RPM and up?
I will report back in a day or two.

[miker98038]

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The number on the distributor will give the total centrifugal advance, and the slope it comes in by rpm, the total vacuum advance, and how it comes in by inches of vacuum, and the general mechanical info such as end play and side play in the bushings.

Your right about 8-12* initial and 32-38* all in at 2500-3500 rpm. But that’s typically US small blocks. Over the years I’ve had several engines where everything from the cam, compression, porting, intake and exhaust manifolds were all modified. Factory specs are just a starting point for a good tuner. I’m not that good, but I’ve know people who are.

[KULTULZ]

... in those years and after, premium fuel was sometimes difficult to find and expensive.

!!! !!!

Those were the pinnacle days of HP. You don't remember -

[miker98038]

No K, I remember quite well. About 1970, the Custom Supreme Chevron (which ran right there with Sunoco 260 supposedly, at over 105 octave, sometimes 110) was replaced with unleaded (the “white pump”). 1972 was near the end of the line, at least out here in Wa for cheap real gas. I was reduced to sneaking AV gas out since Dad had a light plane.

I never saw a pump like that, with a selector. That’s cool.

My point is, who knows what happened in the 58 years in the middle to any particular engine, especially high performance ones.

[troutmalt]

WOW - thanks Miker.....
I had no idea - time to get that distributor number tomorrow and let you guys decode it.

[KULTULZ]

I never saw a pump like that, with a selector. That’s cool.

The design had two tanks in the ground, one regular dino juice and the other rocket fuel ... . They were blended in the pump to deliver whatever octane you wanted.

My point is, who knows what happened in the 58 years in the middle to any particular engine, especially high performance ones.

I got to wondering a few minutes ago (as I often do) and found the engine photo. It appears (to me) as a 1968 302 IMCO engine w/ an AUTOLITE (but won't) 4300A carb. The DIST used a dual diaphragm canister for early emission control (advance-retard).

If it is indeed an OEM dist, most likely someone defeated the IMCO DIST by removing the advance canister, closing the bowl somehow (scary) and putting a dual point kit in which was available from FORD at the time. It may be that either the plate(s) are being restricted in movement or the DIST was never re-curved correctly.

The DIST CAP appears to me as being a MALLORY AFTERMARKET.

As for the octane wars, remember SHELL w/ TCP (THOMAS CAT P!SS) and EXXON that turned the top of the carb red and clogged the fuel filter w/ TIGER HAIRS ...

[KULTULZ]

- !!! STOP THE PRESSES !!! -

It seems that KUTULZ (aka MR. KNOW-IT-ALL) has had a serious CRS EPISODE.

The 289 was carried over to the 1968 PRODUCTION YEAR and there was a 289CI/271HP engine available.

I have to have that DIST I.D INFO now ...

SOURCE - https://www.mustangspecs.com/1968-mu...engine-289-v8/

I need to research all of this. For some reason I was under the impression the 302 was the only 1968 SB offered It was actually phased in.

The 4300 CARB was introduced in the 1967 model year.

And I was working at a LM DEALER that year. I am going to have to call the home and make arrangements ...

[miker98038]

Interesting. The info I found (on the internet, so it has to be true) showed the base 289 as an 8.7:1 engine. No other 289 was shown, but the FE’s (390, 427,428 maybe more ) were shown. This makes it a whole different case.

[KULTULZ]

I come before you as a confused and humbled man ...

It seems the SOURCE I referred to is not correct. It was as I thought -

1963-1967 289 K-CODE discussion - https://www.stangnet.com/mustang-for...fusion.796482/

It seems the 289 only made it into 1968 production as a 2V. It was replaced within the 1968 production run with a 302 2V.

There was no 1968 302HP other the the G-CODE TUNNEL PORT which was not released for the street.

That's what I thought. Going into the FORD BIBLE to document this.

I can't understand this as the NET has never lied to me before ...

[Ole Don]

We all need to remember how many years have passed since these engines were new. How many people have tried to make them perform better and put on different parts. In our endeavor to make them fun, we need to study basics and make what we have better, or step up and buy new better parts.

[craig]

Kultulz is correct, the 289 2V carried over about half way thru the '68 production run. When the 302 replaced it, there was a standard 2V version as well as a J code 4V version, unique to '68 only. It was advertised at 230 horsepower, 10 to 1 compression, single point, dual diaphram distributor, thermactor system and a 4300 Autolite carb. I've only seen it in a Mustang (owned one 45 years ago) but was told it made it into a handful of Falcons. As mentioned the K code was gone and the J code was basically a replacement for the non hipo (225 horse) 4V 289.

As far as timing on Troutmalt's engine, it would be nice to see the dist. number so he could see what the specs were for it at production. But here's my take on this. Apparantly it has no vac advance, but did originally(?), if so then the thing will never see a total of 36 degrees with a base of 10. If it did, you would want it at about 1800-2000 rpm, cruising speed, for best vacuum/mileage. Regardless of what the factory specs list, an original K code full mechanical dual point was hard pressed to get a 32 degree total with a 12 degree intial at 5000 rpm, and it was turning alot less rpm's driving 70 mph even with the standard 3:89 gears in a '65-'66 Mustang.
Set your base timing at 10-12 degrees, hook up a vac gauge and bring the throttle up to 4000 rpms, if the vac gauge starts dropping off and the thing miss fires, then you have too much total advance, if not then leave it alone and drive it....Or go out and waste your money on an aftermarket distributor that you can tailor to your desired specs. But I'll let you in on a little secret, if this is a daily or part time driver, not a race car, then it won't run any better than it does now. Drive it, enjoy it

[troutmalt]

Craig - that is super valuable information. If I need a vacuum advance to get the full 36 degrees I am in trouble. For those interested, this engine was ordered by Italia Intermeccanica in Turin Italy in 1968 from Ford Export. The metal tag on the engine says
Ford Industrial Engine:
Serial: 1183-H24KT
Type: 302:GP -6001-OF
Options: 90-1710
Can anyone decode this?
I assumed it was a K code due to the type of exhaust manifolds.
It appears the distributer never had a vacuum pot. ! ? !
As promised I will report distributer number when rain stops.
What an incredible fund of knowledge you guys are for a newbie like me.

[Flathead Fever]

It seems to me the missing degrees of advance is because the vacuum advance is gone. Normally you would check the initial advance with a timing light with the vacuum advance unplugged and you would see your 6-10 degrees of initial advance. Then run the rpm up and check the mechanical advance with an adjustable timing light (only buy a timing light with the adjustable feature and you won't need tape on the pulley). Then you put a handheld vacuum pump on the vacuum advance, pump it up and check the vacuum advance degrees of advance. Add them all up and you have the total advance.

The Ford hipo dual point distributors do not have a hole in the castings for a vacuum advance. The total advance is built into the centrical weights. On a distributer with a vacuum advance the centrifugal weights will have the same amount of advance.

On a hipo 289 with high compression with only a mechanical advance distributer, the fuel mixture will pre-ignite without high octane fuel which most people do not want to pay for. The average person wants the best fuel economy on the cheapest octane gasoline. To prevent low octane fuel from pinging manufacturers, use lower compression engines with a vacuum advance on the distributer. It actually does the opposite of what most people think. Under a heavy load it retards the timing to prevent the cylinders pressures from getting so high that they ignite before the spark plug fires. On a high-performance engine you want the highest pressure on the piston you can create without pre-ignition, so you want the timing advanced at high rpms with the throttle wide-open.


When the throttle is closed you have high intake manifold vacuum (vacuum below the throttle plate), but no venturi vacuum. As the throttle is opened and air starts moving through the venturi, venturi vacuum rises, this starts to operate the vacuum advance at cruising speeds. As the throttle is opened further and the throttle blades no longer cause a restriction, intake and venturi vacuum drops off which causes vacuum advance to retard the timing. This prevents high cylinder pressures that would cause pinging. The vacuum advance only operates at normal cruising speed to give you the best power and fuel mileage. It does not operate at idle or wide-open throttle. Mash the pedal to the floor and it retards the timing as the vacuum drops off. The engine will not ping, but this kills the horsepower. If you're after that horsepower than you install a mechanical advance only distributor and use higher octane fuel.

Whatever somebody did to your distributer only made its drivability at cruising speed worse, less power and less fuel mileage. Since it's not a mechanical advance only distributer it does not have that extra degrees of advance designed into the centrifugal mechanism. If you're not after the power put the correct vacuum advance back on. If you want the power, you will need to get a mechanical advance only distributer. Recently I bought a new Mallory dual point, centrifugal advance only distributer at a swam meet for $20.00. Nobody wanted it because it had points. There is nothing wrong with points, I've used them engines running up to 7000 rpm. They are obviously not as accurate as electronic ignitions but if the points are changed according to factory recommendations, they are dependable. I was a fleet mechanic for 30-years and I can say that probably more vehicles were towed in with faulty electronic ignition modules and pickups than ones with failed points.

[miker98038]

Well, curious and curiouser. It would be interesting to know how that got from wherever to the engine bay of that car. Other industrial engines I’ve been around (not all) didn’t have a vacuum advance, they were expected to run under pretty continuous load. Like the larger number of gasoline marine engines I’ve been around. Anyone want to speculate on a Ford industrial cam shaft? I wouldn’t have a clue.

Wait a minute, that engines not in a Mustang is it? It’s a real Intermeccanica isn’t it. I forgot that?

K see if they’ve got a room down the hall at the home. I’m next.

[chain drive]

i worked at a shell station a tanker load of gas came in i put a 5 gallon can of tcp in the top of the tanker that was the tom cat piss the good days have fun

[KULTULZ]

It would be interesting to know how that got from wherever to the engine bay of that car. Other industrial engines I’ve been around (not all) didn’t have a vacuum advance, they were expected to run under pretty continuous load.

FORD INDUSTRIAL ENGINE -

That answers it. If the DIST is industrial, the engine RPM is constant so no automotive advance(s) is needed and/or vacuum advance.

For the car to drive normally (fully functional advance), you will need to find an automotive DIST.

Somebody did somebody no favors. It wasn't thought out.